I love tom kha soup, although I usually like to eat it as a main course with rice. My sister Cheryl told me that I could actually use tamarind powder (same one I used last week) to make some of my favorite Thai soups. So I gave it a shot and of course she was right! I wish I had some lemongrass on hand but I couldn't convince myself to go outside yesterday so I just used whatever I had around. Slices of red bell peppers and button mushrooms would be perfect in this dish.
I first sautéed ginger and shallots, then added chunks of chicken breast, salt, fish sauce and cooked it until slightly browned.
I added a can of coconut milk and about a tablespoon of tamarind powder and lowered the heat to a simmer, covered it and cooked it for about 30 minutes.
In the meantime, I boiled my veggies (eggplant, string beans, carrots and onions) in chicken stock until tender. I decided that I wanted something less soupy so I didn't add the stock to the end dish - but if you wanted, I suppose you could add the broth to the coconut milk and chicken.
I added a bit of it this for some heat, but I think I was a little too shy with it and should've added more than I did. Calamansi looks like a mini lime but tastes like a cross between a lemon and a mandarin orange.
If you don't have tamarind powder, you can try experimenting and adding white vinegar instead - I've seen some recipes for tom kha using vinegar.
Then just add the veggies to the chicken, taste for seasoning - you many need to add more salt, fish sauce, or tamarind powder.